feat(db): wire migrator into app startup (fail-soft, lazy require)

Migrator runs on app.whenReady before pollers/createWindow. Lazy require
keeps native better-sqlite3 errors from blocking app startup. Result is
logged via appendDebugLog for diagnosis. Verified via npm run test:e2e
(0 issues, app starts cleanly).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/main.ts

@@ -7211,6 +7211,27 @@ app.whenReady().then(() => {
     refreshBundledToolPaths(true);
     startMetadataCacheCleanup();
     startDebugLogFlushTimer();
+
+    // SQLite-Shadow-Migration (Plan 02 / v5.0.0-alpha.1). Idempotent + fail-soft —
+    // bei Fehler bleibt JSON der Master. Lazy require, damit Native-Build-Fehler
+    // den App-Start nicht verhindern.
+    try {
+        const { openDatabase } = require('./main/infra/db');
+        const { migrateJsonToSqlite } = require('./main/domain/migrator');
+        const dbPath = path.join(APPDATA_DIR, 'app.db');
+        const db = openDatabase(dbPath);
+        try {
+            const result = migrateJsonToSqlite({ db, appDataDir: APPDATA_DIR });
+            appendDebugLog('sqlite-migrator', result);
+        } finally {
+            db.close();
+        }
+    } catch (e) {
+        appendDebugLog('sqlite-migrator-failed', {
+            error: e instanceof Error ? e.message : String(e),
+        });
+    }
+
     restartAutoRecordPoller();
     restartAutoVodPoller();
     restartLiveStatusPoller();